<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<style>
div {
    position: relative;
    margin: auto;
    width: 160px;
    line-height: 160px;
    text-align: center;
    font-size: 24px
}
div::before {
        content: "";
        position: absolute;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        border: 2px solid gold;
        transition: all .5s;
        animation: clippath 3s infinite linear;
    }

@keyframes clippath {
    0%,
    100% {
        clip-path: inset(0 0 95% 0);
    }

    25% {
        clip-path: inset(0 95% 0 0);
    }
    50% {
        clip-path: inset(95% 0 0 0);
    }
    75% {
        clip-path: inset(0 0 0 95%);
    }
}

.bg::before {
    background: rgba(255, 215, 0, .5);
}
</style>
<body>
  <div>Hello</div>
<div class="bg">示意图</div>
</body>
</html>